Ladder lock



Feb. 21, 1950 w, MOQRE 2,498,375

LADDER LOCK Filed Sept. 1.9, 1946 2 Shets-Sheet 1 FIE-1* IN VEN TOR.FRANCIS MIA/[00. 22

F. W. MOORE LADDER LOCK FenZL1950 2 Sheets-=Sheet 2 Filed Sept. 19, 1946INVENYTOR. FHA NLI'IEWMU [IRE Patented Feb. 21, 1950 UNITED S TAT ESPATENT OFF 1 CE LADDER LOCK Francis W. Moore, Tiflin, Ohio ApplicationSeptember 19, 1946, Serial No. 697,875

10 Claims.

This application relates to a ladder, the inclination of which isadjustable, and where a lock is provided to hold the ladder in adjustedposition. The particular improvement relates to the lock provided forthis purpose. The object of the invention is to provide a ladder whichmay be locked in adjusted inclination .and securely held at thatinclination until intentionally adjusted, and a lock that can be readilyreleased for adjustment. More particularly, the invention relates to alock where there is pivotal adjustment between parts, and locking camsare provided which prevent such pivotal movement until the cams areintentionally released. Further details of the invention will appear asthe description proceeds.

In the accompanying drawings forming a part of this specification, Fig.1 is a side elevation of the lower part of a ladder which hasstepsthereon automatically maintained in parallel with the .foot of theladder and means to lockthe ladder at adjusted inclination. Fig. 2 is .adetailed view of the lock and one ladder step with the ladder locked atan inclination. Fig. ,3 is a side View of the lock shown in Fig. 2 takenalong the line 3-3 of Fig. 2. Fig. 4 is a side elevation of a rungladder with a foot at the bottom and a shoe at the top which aremaintained parallel, and means for locking the ladder in adjustedinclination to the foot and shoe. Fig. 5 is a side View of a rung ladderhaving a foot and means for locking the ladder in adjusted inclinationto the foot. Fig. 6 a side elevation of another ,form of lock suitablefor use as the lock in Fig. 5', with a portion of the foot removed. Fig.7 is a reduced side I elevation of the lower end of the ladder, shoe andlock shown in Fig. 6 with the cams removed for clarity of illustration.

In the form of ladder shown in Figs. 1, 2 and 3, there is a series ofsteps 1:0,, the upper surfaces of which are normally maintainedhorizontal. For this purpose, there is a side strip H and a side strip[2 to which. the steps are pivoted at l3 and M respectively. It will beseen that adjustment of the relative position of the strips. willsimultaneously adjust the inclination oi all of the steps Ill, since theequal distance apart. of. the pivots on the strips and on the severalsteps and foot enforce a parallel link motion. Suitably mounted on stripH- there are pivotv pins [5, l6 and I! 3:

v2 vided with an arm 24 pivoted to strip [.2 at 125. It will be notedthat the axes of the cams are parallel and spaced to permit contactbefore the rises vof the cam directly face each other.

Normally, the ladder is supplied with afoot 2.6 which has a lowersurface parallel with'the upper surfaces of steps Ill and which :ispivoted 'to strips I land 42 by pins-21 and .28 respectively.

It will be seen that, when foot 216 rests on a horizontal surface, steps10 will have upper hori zon-tal surfaces :at' whatever-angle to thevertical strips II and I2 may be adjusted.

Presuming that the ladder has been adjusted to either the verticalposition in which it is shown in Fig. 1 or to the slanting position inwhich it is shown in Fig. 2. it will be readily seen that attemptedmovement of the top of the ladder to the left will be resisted bycontact of cams '19 and 20, while attempted movement of the upper .endof the ladder to the right will be resisted by contact of cams l8 andI9. When adjustment of the ladder is to be made,,the respective cam 180126 which resists the desired movement of the ladder is released bymeans of projecting pin 21 or 22 which extend outward to form releasinghandles. Thus, by simple release of the appropriate cam, the ladder canbe readily adjusted and, when in adjusted position, the spring .23retainsthe locking cams in contact with camlBso as to prevent movementof the ladder in either direction.

In the construction shown in Fig. 4, there is a similar foot 26 with itspivots f2! and 2B, but instead of strips 1 l and 12 there is a mainladder side strip 30 provided with rungs 3| and 32 .and an adjustingstrip .33 connected to pivot 28. A shoe .34 at the upper end of theladder is pivoted'to strip 30 at and to strip 33 at 36. The shoe 34 isthus maintained in proper relation with foot 26 so that, when foot 26rests upon a horizontal surface, the left side of shoe 34, as shown inFig. 4, will be vertical and may rest against any upright surfaceagainst which the ladder is leaned.

In this case, thestrip 30 is provided with a plate 31 carrying pivots.38- and39 on which there are pivoted cams 4-0 and 41 provided withpins, and .43 connected by asprin-g 44. Cam 4] is provided with an arm45 pivoted at 46 to strip 33-. In the form shown, it will be seen thatthe contact of cams 4D and 4| will resist'movement of th upper-end ofthe ladder to the left but the cams maybe readily released foradjustment by movementof cam 48 by the extendedv handle 'justm'ent inboth directions.

It will be seen that this look operates substantially the same as thelock shown in Figs. 1 to 3 except that it is locked against movement inone direction only. An additional locking cam, as shown in Fig. 1, mightbe used with this form of ladder, and the ladder shown in Fig. 1 couldbe supplied with a one-way lock only, if desired.

Fig. shows a look similar to that shown in Fig. 4 where the ladderconsists of sidepieces 50 and rungs 5| with afoot 52 to which the sidestrip is pivoted at 53. In this case, cam 54 surrounding pin 53 isattached to turn with strip 50 about the pivot. A cam 55 is pivoted tothe foot at 56. Pin 51 on cam 54 is connected to pin 58 on cam 55 bymeans of a spring 59. It will be seen that the spring normally holds cam55 in contact with cam 54 and that-the contact of these cams will lockthe ladder against movement of the upper end of the ladder to the left,as viewed in Fig. 5. When it is desired to adjust the'upper end to theleft, extended pin 58 may be employed as a handle to release cam 55 sothat the required adjustment may be made.

Figs. 6 and 7 illustrate a construction in which there is a ladder sidestrip 60 mounted on a pin 6| in a foot 66, similar to the arrangement inFig. 5, but in which the ladder is locked against movement in eitherdirection and throughout a wide range of movement, so that the laddercan be adjusted to any position about pin 6i and locked in that adjustedposition against movement in either direction.

In this case, there are cams 52 and 63 keyed to'pin 6| along with sidestrip 60 so that all turn together. The throws of cams 62 and 63 are inopposite directions. Arranged symmetrically about pin 6| there are pins64, 65 and 66 mounted in the foot 60. Onpin 65 there is a cam 61 havingthereon a pin 68. On cam 62 there is a pin 69 connected to pin 68 byspring 10 which urges cam 61 into contact with cam 62. On pin 66 thereis a, cam 1|, having a pin 12 connected to a pin 73 on cam 62 by aspring M. On pin 64 there is a cam 15 having a pin 16 connected to a pin1'! on cam 62 by a spring I8. It will thus be seen that these cams 61, Hand 15 are all normally urged into contact with cam 62. In theconstruction shown, cam H will resist move- .ment of the upper end ofthe ladder to the right,

while cam 15 will resist movement of the ladder to the left.

Similarly, there are cams I9, 89 and 81 held in contact with cam 63 bymeans of springs,

springs 82 and 83 being shown, but the spring in connection with cam 19being behind the cams and so not visible. It will be noted that cam 80will resist the movement of the top of the ladder to the left while cam8| will resist the movement of the top of the ladder to the right.

As will be seen, by the construction disclosed in Figs. 6 and '7, thecentral cam may turn through any angle and still be locked at any ad-The cams may be released by separate movement of their pins but, ofcourse, in practice some suitable-means not shown could be employed forsimultaneously releasing the cams that lock the ladder against movementin the direction in which adjustment was desired.

It will be noted that, in each instance, the lock is accomplished bypreventing the rotary movement of a locked cam in contact with one ormore locking cams, with the locking cams spring-held against the lockedcam, and the lock being releasable by movement of each spring-x held camin opposition to the spring. In the preferred form shown in Figs. 1 to'3, there are three cams, the central one of which is locked by theother two. In the construction shown in Figs. 4 and 5, there are but twocams, and the lock is operative in only one direction. In theconstruction shown in Figs. 6 and 7, there are two central cams and theyare locked continuously in both directions by a series of locking camsthere around, in this instance three locking cams for each locked cam.With the three cams arranged as indicated in Fig. 6, the central camsare constantly locked at any angle to which they may be adjusted.

While primarily designed for use in combination with a ladder,particularly in such a combination as shown in Figs. 1 to 3, the lockmay be capable of application in other combinations where similardemands are to be met. While several modifications have been shown anddescribed, it will be understood that other changes may be made withinthe scope of the appended claims while retaining some of the advantagesof the invention.

What I claim is:

1. In a ladder having side strips and a member pivotally mounted on saidstrips, a locked rotary cam connected to the strips and member to beturned by pivotal adjustment of the strips and member with respect toeach other, and a locking cam oscillatable about an axis which is at afixed distance from and parallel with the axis of the locked cam,resilient means normally pressing the locking cam against the locked camwith the rises of the cams so related that turning of the locked cam inone direction tends to bring their rises together, and means to turn therise of the locking cam away from the locked cam.

2. In a ladder having side strips and a member pivotally mounted on saidstrips, a locked rotary cam connected to the strips and member to beturned by pivotal adjustment of the strips and member with respect toeach other, and a locking cam oscillatable about an axis which is at afixed distance from and parallel with the axis of the locked cam, pinsprojecting from the cams on the same sides of their axes as their rises,and a spring connecting the pins, the pin on the locking'cam'beingextended to form a handle for releasing the lock.

3. In a ladder having side strips and a member pivotally mounted on saidstrips, a locked eccentric cam connected to the strips and member to beturned by pivotal adjustment of the strips and member with respect toeach other, and an eccentric locking cam oscillatable about an axiswhich is at a fixed distance from and parallel with the axis of thelocked cam, pins projecting from the cams in the same sides of theiraxes as their rises, and a spring connecting the pins, the pin on thelocking cam being extended to form a handle for releasing the lock.

4. In a ladder having a foot pivoted thereto, a lock for locking theladder in adjusted pivotal relation to the foot comprising an eccentriclocked cam and at least one eccentric locking cam, said cams beingmounted so that the locked cam is turned with respect to the axis of thelocking cam when the pivotal relation of the foot and ladder is changed,resilient means pressing the locking cam against the locked cam in adirection to move their rises together, and means to move the rise ofthe locking cam away from the locked cam for adjusting the angle of thefoot 'tothe 1adder." I

5. In a ladder having a foot pivoted thereto, a lock for locking theladder in adjusted pivotal relation to the foot comprising an eccentriclocked cam and at least two eccentric locking cams, said cams beingmounted so that the locked cam is turned with respect to the axis of thelooking cams when the pivotal relation of the foot and'ladder ischanged, resilient means pressing the locking cams against the lockedcam in a direction to move their rises together, and means to move therises of the locking cams away from the locked cam for adjusting theangle of the foot to the ladder.

6. In a ladder having a foot pivoted thereto, a lock, for locking theladder in adjusted pivotal relation to the foot, comprising lockedeccentric cams mounted to be turned by adjustment of the ladder withrespect to the foot and with their rises extending in oppositedirections, three eccentric locking cams equally spaced around eachlocked cam, and resilient means urging the looking cams against thelocked cams with their rises so arranged that the turning of the lockedcams is resisted in both directions at any position to which the lockedcams are adjusted.

7. In a ladder comprising two parallel side strips at each side of theladder and steps pivoted to said strips by pivots equally spaced on thetwo strips and on the several steps, providing a parallel linkadjustment, a lock for locking the ladder in adjusted position, saidlock comprising three eccentric cams mounted on one of the strips onparallel axes, an arm extending from the middle cam and pivoted to theother strip, resilient means urging the outer cams against the middlecam" with their rises in such relation that turning the "middle cam onits pivot in one direction is resisted by one of the side cams andturning it in the other direction is resisted by the other cam, andmeans for moving the rise of either side cam away from the rise of themiddle cam.

8. In a ladder comprising two parallel side strips at each side of theladder and steps pivoted to said strips by pivots equally spaced onthe'two strips and on the several steps, providing a parallel linkadjustment, a lock for locking the ladder in adjusted position, saidlock comprising three eccentric cams mounted on one of the strips onparallel axes, an arm extending from the middle cam and pivoted to theother strip, the rises of all three eccentrics being on the same side oftheir axes, resilient means urging the rises of the outer cams towardthe middle cam, and means'to move the rise of either outer cam away fromthe middle cam for adjusting the ladder.

9. In a ladder having two side strips at each side of the ladder, stepsand a foot pivoted to the stripsby pivots equally spaced on the twostrips on each side; and on the several steps and foot,

the foothaving a flat bottom and each step hav ing a flat' topmaintained parallel with the said fiat bottom by the parallel linkmotion about said pivots, a lock for locking the strips, steps and footin adjusted relation, said lock comprising three eccentric vcams mountedin a row on parallel axes on one or said strips with their risesextending from the? same side of their axes, resilient means to urge therises of the outer cams towards the rise of the middle cam, theperimeter of the outer cams being normally in contact with the middlecam, and an arm extending from the middle cam and pivoted'to the otherstrip on the same side of the ladder.

10. A lock'f or pivotally related parts comprising an eccentric lockedcam mounted on one of said parts, an eccentric locking cam mounted uponan axis parallel with the axis'of the locked cam, the axes'-of the camsbeing at a fixed distance apart permitting the peripheries of the camsto meet before the rises are directly towards each other, resilientmeans urging the rise of the locking cam towards the rise of the lockedcam, and means forcing the locked cam to turn when the pivotal relationof said parts is changed.

FRANCIS W. MOORE.

REFERENCES CITED UNITED STATES PATENTS Name Date Shain May 26, 1891Number

